The Contribution of Oil to Carbon Particle Emissions from Diesel Engines

Tornehed, Petter

Scania CV.

2010 (English)Report (Other academic)

Abstract [en]

Reducing particle emissions from diesel engines has been an important issue in recent decades. This study assesses the contribution of oil to carbon particle emissions by reviewing the literature and theory on fuel soot formation, and combining it with estimates based on a maximum and minimum approach.

The study shows that the minimum oil contribution to carbon particle emissions for a Euro 5 heavy-duty diesel without exhaust aftertreatment is around 0.4 mg/kWh. The corresponding maximum estimate is 1.1 mg/kWh.

Tornehed, Petter

Abstract [en]

Particulate emissions from diesel engines have been a key issue for diesel engine developers in recent decades. Their work has succeeded in reducing the exhaust particles from the combustion of fuel, which has led to increasing interest in the contribution of particulates from lubrication oil.

When discussing oil-related particulate emissions, hydrocarbon particles are customarily referred to. This thesis uses a broader definition, in which oil-related particulate emissions are modelled not only by the hydrocarbons, but also include the ash, carbons, and sulphate oil particulate emissions.

The model developed in the project uses input data as oil consumption and oil ash content combined with tuning parameters, such as the oil ash transfer rate (ash emissions divided by oil consumption and oil ash content). Controlled engine tests have been performed to verify assumptions and fill knowledge gaps. The model can be applied to a variety of diesel engines, although the tuning factors might have to be reset. For example, introducing diesel particulate filters would dramatically reduce the oil ash emissions, since oil ash would accumulate in the filter.

Oil consumption has played a central role in the present research. The modelling results indicate that special attention should be paid to oil consumption under running conditions with a low in-cylinder temperature, since the oil survival rate is high there.

Under low-load and motoring conditions, hydrocarbons proved to be the main contributor to oil-related particulate emissions. At high engine load, oil ash emissions were the largest contributor to oil-related particulate emissions.